Protection of propeller blades



Nov. 9, 1943.

J. F. MORSE ET AL 2,334,118 PROTECTION OF PRO PELLERBLADES 7 Filed March28, 1939 2 Sheets-Sheet 1 Jahn F ZZ E027 L Tay/aa Nov. 9, 1943. J. F.MORSE ETAL 2,334,118

PROTECTION OF PROPELLER BLADES 2 Sheets-Sheet 2 Filed March 28, 1939rzLfTvibzi 4 Jahn EJ251255 flysan .L 7755 [0 Patented Nov. 9, 1943PROTECTION OF PROPELLEB BLADES John F. Morse and Myron L. Taylor,Hudson,

Ohio, assignors to The B. F. Goodrich Company, New York, N. Y.,acorporation of New York Application March 28, 1939, Serial No. 264,575

19 Claims.

This invention relates to the protection of propellers, especially theblades of airplane propellers, and the invention provides improved meansfor preventing the accumulation of ice on propeller blades.

Because the accumulation of ice upon the blades of airplane propellersobjectionably afi'ects balance, causes undesirable vibration, reducesaerodynamic efficiency and is undesirable also in other respects theprovision of means for effectively preventing ice accumulation onpropeller blades is important.

A device used for resisting ice'accumulation heretofore, known as theslinger ring," has comprised an annular trough-like structure at the hubof the propeller with supplying means for the trough and a short metaltube leading from the outer periphery of the trough to a position at theroot of the blade. An anti-freeze liquid, fed into the trough andconducted radially outward under the action of centrifugal force, hasbeen discharged at the root of the blade for the purpose of spreadingupon the blade to loosen ice accumulated thereon to prevent theaccumulation of ice. Such device has had the disadvantage that thedesired degree of uniformity of distribution of liquid upon the bladehas not always been effected, the liquid often having been blown away byflow of the air without adequate distribution upon the blade, and atbest the liquid has covered only an undesirably small area of the blade.v

Also, the bare propeller blades heretofore have been subjected toundesirable abrasion asa result of impact by dust, stones, and othermatter in the air, especially in the case of metal propeller blades, thenicks of such abrasion having tended to weaken the propeller blade whichis considerably stressed at its surface, and having required frequentreworking and replacement of the blades to maintain adequate safety andefllciency of operation.

a The chief objects of the present invention are to provide improvedprotection of the blade, to

from the following description, reference being had to the accompanyingdrawings in which:

Fig. 1 is a front elevation of a two-bladed airplane propeller assemblyhaving mounted thereon protective means constructed according to andembodying the invention. For convenience of illustration, the left-handblade is shown protected according to one embodiment of the inventionand the right-hand blade is shown protected according to anotherembodiment of the invention, it being preferred that in a particularinstallation, all the blades will be protected uniformly by the sameconstruction.

Fig. 2 is a plan view on an enlarged scale of a portion of theassemblyof Fig. 1, including a portion of the hub and right-hand blade,parts being broken away.

Fig. 3 is a rear elevation of the structure of Fig. 2. Fig. 4 is a planview of the fluid-conducting structure of Fig 2, the parts being shownin their flat state before application to the propeller blade, and partsbeing broken away.

Fig. 5 is a section taken along the line 5-5 of Fig. 4.

Fig. 6 is a section taken along the line 6- -B of Fig. 4.

Fig. '7 is a section taken along the line |--'I of Fig. 1.

Fig. 7A is a section taken along the line la-10 of Fig. l.

Fig. 8 is a section taken along the line 8-8 of Fig. 4.

Fig. 9 is a perspective and sectional view of a modified form of bladeprotective strip shown in its fiat state before its application to thepropeller.

Fig. 10 is a plan view of a further modified form of blade protectingstrip shown in its fiat state beforeits application to the propeller.

Fig. 11 is a section taken along the line ll'-l| of Fig. 10.

Fig. 12 is a section taken along the line I2--i2 of Fig. 10-.

Fig. 13 is a fragmentary view of the under side of the strip of Fig. 10.

Fig. 14 is a cross section'of the leading edge of a propeller bladehaving the strip of Fig. 10 mounted thereon, parts being broken away.

Fig. 15 is a perspective and sectional view of a still further modifiedform of protective strip shown in its flat state before its applicationto the propeller.

still further modified construction.

along its leading edge and for releasing .suclr liquid at spaced-apartpositions along the blade in such manner that the liquid will be causedby the movement of the blade to flow over the surface thereof to loosenice accumulated thereon or to prevent the accumulation of ice. The

distribution and release of the liquid along the.

blade is effected in such a manner that minimum of the liquid isreleased to the air without first flowing over the blade surface, and ina manner such that the liquid is well distributed over the surfaces thatare subject to ice accumulation.

The protective covering or shoe preferably is.

of vulcanizable rubber-like material, such for example as rubbercomposition, neoprene or other so-called synthetic rubber, or evennon-vulcanizable rubber-like material such as plasticized vinylchloride, which materials may be molded to shape and have high abrasionresistance, but the liquid-distributing passageways may-be provided incoverings of wood, metal or other suitable material, or even in theblade proper, if desired.

Provision is made for conducting the liquid to the distributingpassageways while permitting adjustment of the blade in a variable pitchpropeller. Further provisions will be apparent as the descriptionproceeds.

In Fig. 1 the invention, in two alternative embodiments is applied tothe blades 20, 2| of the two-bladed propeller mounted upon a hubstructure 22 having mechanism therein for varying the pitch of thepropeller blades, which pitch-varying mechanism may be of any suitableconstruction.

At the leading edge of blade 20 is mounted a shoe 23 extending along theblade for a sufficient distance to include the icing region. Ordinarilyabout two-thirds of the length of the blade from the root toward the tipis sufficient, but if desired the shoe may extend a lesser or greaterdistance alongthe blade, or even throughout the whole length of theblade if desired. The shoe 23 preferably is of rubber-like material, ashereinbefore described, which material may be readily molded orotherwise formed to provide passages for conducting fluid, and

h which material is readily attachable to propeller blade surface by astrong adhesion or.

bond, and which further has the advantage of good resistance toabrasion. In the embodiment of Figs. 1 to 8 the shoe 23 is formed in itsouter surface with a plurality of grooves 24, 24, 25, 25, 26, 2B, and21, 21 extending peripherally outward from the root portion, these setsof grooves terminating at spaced-apart positions along the shoe, andeach groove terminating preferably in a gradually sloping end surface 28as shown in Fig. 8. The sloping bottom 28 of the groove has theadvantage that the liquid will spill out of thegroove gradually ratherthan abruptly and over a considerable zone. 'If desired, the slope 28may be extended, or the groove may be otherwise gradually constrictedover a zone nearing or even overlapping the end of an adjacent groove toprovide for releasing the liquid evenly all along the shoe.

The shoe may be of small thickness so as not to have a considerable massitself subject to the centrifugal force, and the margins of the shoe arebevelled as at 29 and 30 sothat the surface of the shoe will merge withthe surface of the propeller blade. The shoe may be molded or otherwiseformed in the flat and then fitted to the contour of the blade, to whichit is ad- .hered by an adhesive 3| which may be of a vulcanizable cementor a so-called air-curing cement or any other suitable adhesive.

For conducting the liquid into the grooves, a manifold strap 32 isprovided'at the inner end of the shoe 23. extending transversely theretoand adapted to be wrapped around the propeller blade at its root. Themanifold 32 may be molded or otherwise formed of the same material asthe shoe andpreferably is vulcanized integrally with the shoe. Thegrooves of the shoe communicate with a manifold passage 33 of the strapwhich passage conducts liquid from an inlet nipple 34. A suitable fabricreinforce- .ment 35, preferably of square woven fabric, may

be incorporated in the strap 32, and if desired a similar reinforcement36 may be provided beneath the grooves in the shoe 23 and may extend thefull length thereof. The strap 32 has a raised central portion 31 withdepressed sides 38, 39, the latter being for the accommodation ofholding bands 46, M respectively, encircling the root of the propellerblade. These bands may be of metal having their ends bolted as shown inFigs. 2- and 3 or they may be of ad hesive tape pr any other suitableconstruction.

At the rear of the propeller hub is provided an annular trough 42,itself of known construction, for picking up liquid deposited in it froma non-rotating feed pipe, and for transmitting the liquid outwardly atits periphery to a discharge nipple 43. In accordance with the inventionthere is provided a flexible hose connection 44 of rubber or otherflexible material, between the nipple 43 of the trough 42 and the nipple34 of the manifold, to conduct the liquid from the trough into themanifold which feeds the liquid into the grooves of the distributingshoe. Owing to the flexible connection 44 adjustment of the propellerblade to vary its pitch is permitted, while feeding of the liquid ismaintained. Several positions of the flexible connection 44 for variouspositions of propeller blade adjustment are indicated in broken lines inFig. 3.

In operation, the ice-inhibiting liquid, which may be of a mixture ofglycerine and alcohol or any other suitable substance, is fed into theannular trough 42 from which the liquid is fed by centrifugal forcethrough the flexible connection 44 into the manifold 33 from which, alsoby-c'entrifugal force, the liquid is conducted peripherally outwardlythrough the grooves of the shoe 23. Normally the liquidtravels'peripherially outward and is discharged at the ends of thegrooves where it spills over, wetting the surface of the mulated uponthe blade before the supply of the liquid is turned on, the liquid willbe conducted in I Fig. 1 and in Fig. 7A, where the fabric reiniorce-.

ment of the shoeis continued beyond the margins of the shoe and isextended at 45 entirely around the propeller blade. The fabric,preferably rubberized or otherwise coated to present a smooth outerface, is fitted closely to the blade surface and its margins are securedpreferably by 'a' secured, and preferably the fabric and shoeare adheredto the blade throughout the contacting area. At its outer periphery thefabric preferably terminates in an oblique edge 41 to minimize thelikelihood of developing a vibration node. It will be understood thatwhichever embodiment is used for a given propeller installation allblades thereof should preferably be protected by similar constructionsand that the whole propeller assembly should be dynamically balanced inaccordance with the best practice.

In the embodiment of Fig. 9 the distributing shoe 50, instead of havinggrooves at its surface for conducting the liquid, has continuouspassages, 58 extending within the shoe which passages communicate withthe surface'of the,

surface of the shoe rather than in the outer surface thereof so that theconducted liquid is in direct contact with the surface of the propellerproper while it is being conducted and when it is released from thepassageways. This has the advantage that when the liquid is exposed tothe air flow it is already in contact with the material of the propellersurface itself for effectively wetting the same and has less likelihoodof being blown off until after it has spread considerably on suchsurface. In this embodiment the outside grooves 6i, ti, 62, 62, and 63,63 are curved to terminate in the tapered margins of the shoe todischarge the liquid at the side margins of the shoe While the innermostgrooves extend to the tip of the shoe. The outer grooves may beflattened toward such margins and flared as shown in Figs. 10 and 13without restricting the sectional area of the passage so that dischargeand spreading of the fluid along the blade surfaces will be facilitated.Two central passageways 6 l, 66 may extend to the tip of th shoe fordistribution of the liquid beyond the end of the shoe.

As shown in Fig. 14 the shoe 6!! is of such shape that it merges withthe outline of the propeller blade 65, and the latter may be provided insuch a shape that when the shoe 60 is added the outer surface of thecomposite structure provides the desired aerodynamic characteristics.The shoe 6!! may be secured to the blade surface by adhesion. Ifdesired, additional means may be provided for reinforcing the shoe andfor securing it to the blade, for example, a fabric as described inconnection with the embodiment for the lefthand blade of Fig. 1. Such afabric should be embedded in the material of the shoe between the outersurface thereof and the grooves so as not to interfere with the latter,and the side openings in the shoe may be made through such fab- I ric.

In the embodiments of Figs. 15 and 16 provision is made for conductingthe liquid'along both faces of the shoe. Fig. 15 shows a shoe 10 inwhich a series of grooves H, H is provided in the outer surface of theshoe and a series of grooves 12, 12 is provided in the underneathsurface of the shoe, this embodiment being a combination of theembodiments of Figs. 1 to 8 and 10 to 14. If it is desired to includethe fabric reinforcement in this embodiment the reinforcement may bedisposed between the upper and lower sets of grooves so as not tointerfere with the flow of the liquid. In Fig. 16 grooves 13, 13 areprovided only in the lower surface of a shoe 14 and connection with theouter surface of the shoe is provided by through apertures 15, 15 in theareas desired.

The separately formed shoe of rubber-like ma terial having the liquidconducting passages therein has the advantages of making for greaterpropeller strength and by leaving it intact, and providing for greaterabrasion resistance at the leading edge, but if'desired, the liquidconducting passage may in some cases be provided in the surface of thepropeller blade itself, whether the latter be of metal, wood, moldedcomposition, or other material. In Figs. 17 and 18 is illustrated suchan application of the invention. A blade has a plurality of grooves 8|,BI, 82, 82, 83, 83, and as, 84 formed in the surface of the leading edgethereof extending outwardly from the root of the blade and terminatingat spaced apart positions along the same. A manifold 85 having aflexible connection 86 to a distributing trough, as in the case of themanifold illustrated in Figs. 1 to 4 has an internal manifold spacecommunicating with the several grooves in the blade surface. Thismanifold may be of molded rubber or other rubher-like material or ofmetal, wood, orany other suitable material and. may be adhered, strappedor otherwise secured upon the root'of the propeller blade.

Variations may be made without departing from the scope of the inventionas it is defined in the following claims.

We claim:

1. Liquid-distributing means for the surface of a propeller bladecomprising a cover structure of rubber-like material adapted to bemounted upon the leading edge of the blade with a surface of rubber-likematerial exposed at said leading edge, said structure having a pluralityof liquid-conducting passageways in the material of the cover structureextending along the same and in communication with said exposed surface.

2. Liquid-distributing means for the surface of a propeller bladecomprising a cover structure adapted to be mounted upon the leading edgeof the blade, said structure having a plurality of liquid-conductingpassageways in the material of the cover structure extendingalong thesame from a portion thereof nearest the root of the blade when mountedtherein, and manifold means at the said portion for feeding liquid intosaid passageways, said manifold means comprising, a conduit extendingtransversely of said pas adapted to be mounted upon the leading edge ofthe blade, said structure having a plurality of liquid conductinggrooves extending along the exposed surface of said cover structure.

4. Liquid-distributing means for the surface of a propeller bladecomprising a cover structure adapted to be mounted upon the leading edgeof the blade, said structure having a plurality of liquid conductinggrooves extending along the exposed surface of said cover structure andterminating at spaced-apart positions along said surface.

5. Liquid-distributing means for the surface of a propeller bladecomprising a cover structure of rubber-like material adapted to bemounted upon the leading edge of the blade with a surface of saidrubberlike material exposed at said leading edge, said structure havinga plurality of individual conducting passages beneath the surfacethereof extending along. the same and communicating with the exposedsurface of said structure at spaced-apart positions along the same.

6. Liquid-distributing means for the surface of a propeller bladecomprising a cover structure adapted to be mounted upon the leading edgeof the blade with its margins intermediate the leading and trailingedges, of the blade, said structure having at least one liquidconducting passageway beneath the surface thereof in the material of thecover structure extending along the same and open unrestrictedly at themargin of said cover structure.

'7. Liquid-distributing means for the surface of a propeller bladecomprising a cover structure adapted to be mounted upon the leading edgeof the blade, said structure having at least one liquid conductinggroove in the underneath surface of the cover structure extending alongthe same from its root portion and communicating with the surface ofsaid structure at its margin to conduit the liquid along the groove incontact with the propeller blade and release the ture connecting saidgroove with 'the outer surface thereof.

9. A protective covering for a blade of a propeller comprising a body ofrubber-like material adapted to be adhered to the blade at the leadingedge thereof, said body being contoured to provide its outer exposedsurface as the aerodynamic surface of the leading edge, and at leastoneliquid-conducting groove in said outer exposed surface of therubber-like material.

10. A protective covering for a blade of a pro-' peller comprising abody of rubber-like material adapted to be adhered to the blade at theleading edge thereof with a surface of the rubberlike material exposedat the leading edge of the blade, said body having at least one liquidconducting passage in the rubber-like material of said body extendingalong the same from a portion thereof nearest the root of the blade whenmounted thereon adapted to receive liquid at said portion and todistribute the liquid upon the blade at a position peripherally outwardfrom said portion.

11. A protective covering for a blade of a propeller comprising a bodyof rubber-like material, passage means in the material of said body forconducting liquid from a portion of said body nearest the root of theblade when mounted thereon to a position peripherally spaced therefromand combined strap and manifold means adapted to extend about thepropeller blade at its root portion for securing saidbody to the bladeand feeding liquid to said passage means.

12. A protective covering for a blade of a propeller comprising abody'of rubber-like material,

passage means in the material of said body for conducting liquid from aportion of said body nearest the root of the blade when mounted thereonto a position peripherally spaced there from, means adapted to extendabout the propeller blade for securing said body to the blade,

and manifold means at said portion of said body I for conducting liquidto said passage means, said manifold means comprising a conduitextending transversely of said passageways and in communication with thepassageways.

13. A protective covering for a blade of a propeller comprising a bodyof rubber-like material extending along the blade at the leading edgethereof and having margins disposed intermediate the leading andtrailing edges of the blade, and means comprising a strap secured tosaid body at the root portion and extending around the trailing edge ofthe blade for securing said body to the blade.

14. In an airplane propeller construction, a propeller blade comprisinga propeller body of one material having the general shape and contour ofthe desired propeller air foil, a layer of surface material upon atleast the leading edge of said propeller, the contour of the surface ofwhich layer completes the desired air foil contour of the finishedblade, and a plurality of grooves formed in said layer material andextending different distances longitudinally along said blade from thehub end thereof.

15. In a propeller construction, a blade comprising a blade body havinga desired air foil contour, a plurality of anti-icing-liquid conduitsextending longitudinally of said blade and terminating at differentdistances along the leading edge of said blade spaced from the hub endthereof for uniformly distributing anti-icing liquid along said blade.

v 16. In a propeller construction, a blade comprising a blade bodyhaving a desired air foil contour, a layer of surface materialassociated with said blade body and having formed therein a plurality ofanti-icing-liquid conduits extending longitudinally of said blade, saidconduits terminating at different distances alcng the leading edge ofsaid blade spaced from the hub end thereof for uniformly distributinganti-icingliquid along said blade. l

2,334,118 18. In a propeller construction, a blade structure having adesired airfoil contour and a plurality of anti-icing-liquid conduitsextending longitudinally of said blade structure and terminating atdifl'erent distances along the leading edge thereof for distributinganti-icing-liquid along said blade structure.

19. In a propeller construction, a blade structure having a desiredairfoil contour and a. plurality of anti-icing-liquid grooves extendinglongitudinally in the surface of said blade structure and terminating atdifferent distances along the leading edge thereof for distributinganti-icing liquid along said blade structure.

JOHN F. MORSE.

MYRON L. TAYLOR.

CERTIFICATE or CORRECTION. Patent No. 2,53h,11 November 9, 1915.

JOHN F. HORSE, ET AL.

It is hereby certified that error appears in the printed specificationor the above numbered patent requiring correction as follows; Page 1,first column, line 21+, for "to prevent read or preventing-; page 2,first column, line 18, for such a manner that" read --such a manner thata-;

page LL, first column, line 19, claim 5, for "passages beneath readpassages in the material of the, cover structure beneath; and that thesaid Letters Patent should be read'with this correction therein that thesame may conform to the record of the case in the Patent Office.

Signed and sealed this 1st day of February, A. D. 19%.

Henry Van Arsdale, (Seal) Acting Commission-= of Patents-

